In one example of a conventional dispensing device, processing is performed collectively using a plurality of specimens and reagents each with a relatively small volume (from several hundred microliters to several thousand microliters) (Japanese Patent No. 3,115,501, International Patent Publication No. WO96/29602, International Patent Publication No. WO97/44671). This dispensing device handles relatively small volumes of fluid by fitting a plurality of pipette tips having the capacity mentioned, to a plurality of nozzles, and laying out not only a large number of containers with this capacity, but also a large number of unused and used pipette tips, and repeating an automatic process of fitting and detaching the pipette tips to and from the nozzles. In this dispensing device, so that suction and discharge can be performed by adjusting the pressure inside the pipette tip, the construction of the pipette tip is made simple by fitting the pipette tip to a nozzle which connects to a separate cylinder equipped with a plunger.
Thus, when handling relatively small volumes of fluid, even when the attachment and removal of pipette tips is repeated with not only a large number of pipette tips but also a large number of containers laid out, because the capacity of each pipette tip and each container is relatively small, a great deal of working space is not required. Furthermore, even when the pipette tips and cylinders are provided separately, they do not take up a large area.
Incidentally, when attempting to handle relatively large volumes of fluid greater than several tens of milliliters when there is a large number of inspection articles such as specimens to be tested, if a dispensing device is used which handles small volumes of fluid as described above, the processing cannot be performed all at once, and the fluid must be handled in smaller units. As a result, dispensing must be repeated a large number of times which is cumbersome. Furthermore, there is a problem in that for the sake of automation, a large number of used and unused pipette tips, as well as a large number of small capacity containers must be laid out, which may necessitate a large working space.
On the other hand, when a pipette tip with a large capacity is fitted to a nozzle, the volume of air used to adjust the pressure can be as much as the total of the capacity of the pipette tip, the capacity of the nozzle, and the capacity of the tube that connects to the separate cylinder. Taking into consideration that the volume of gases such as air is more variable to pressure and temperature than fluids, a problem occurs in that the increase in the amount of air to be handled due to the increase in capacity of the pipette tip causes a deterioration in the accuracy of the suction and discharge operations. Furthermore, it is necessary to provide not only a large capacity pipette tip but also a separate similarly large capacity cylinder for adjusting the pressure within the pipette tip, as well as a large number of large capacity containers to be used, and if the processing is to be automated, unused and used large capacity pipette tips in an detachable manner. Therefore there is a problem in that a vast working space may be required.
To solve the above problems, a first object of the present invention is to provide a dispensing cylinder, a large capacity dispensing device, and a method of using a large capacity dispensing device, which can perform processing with excellent quantitativity and high reliability despite handling relatively large volumes of fluids (greater than several milliliters, for example several ten to several hundred milliliters) for a large variety of inspection articles.
A second object is to provide a dispensing cylinder, a large capacity dispensing device, and a method of using a large capacity dispensing device, capable of suppressing the scale of the device and efficiently utilizing working space despite the large volumes of fluid handled.
A third object is to provide a dispensing cylinder, a large capacity dispensing device, and a method of using a large capacity dispensing device, in which cross contamination of inspection articles can be reliably prevented, the safety of the operator is considered, and ease of handling is achieved.
A fourth object is to provide a dispensing cylinder, a large capacity dispensing device, and a method of using a large capacity dispensing device, which have a simple construction at low price.
A fifth object is to provide a dispensing cylinder, a large capacity dispensing device, and a method of using a large capacity dispensing device, in which a variety of processing of relatively large volumes of fluid can be performed quickly and efficiently for a large number of inspection articles.